Vietnam Academy of Science and Technology: Journals Online
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CHEMICAL CONSTITUENTS FROM POLYGONATUM KINGIANUM COLL. ET HEMSL. OF VIETNAM
No full textSeven compounds, including two homoisoflavanones 3-(2ʹ-hydroxy-4ʹ-methoxy-benzyl)-5,7-dihydroxy-8-methyl-chroman-4-one (1), disporopsin (2) along with 2-O-methyl-α-D-fructofuranose (3), (E,E)-9-oxooctadeca-10,12-dienoic acid (4), 1-palmitoylglycerol (5), 5α,8α-ergosterol peroxide (6), daucosterol (7) were isolated from the rhizomes of Polygonatum kingianum of Vietnam. Their structures were determined by 1D and 2D NMR spectra and by comparison with the reported spectral data. Compounds 3, 4 and 6 are first reported from the genus Polygonatum. Compound 1 and 5 are reported for the first time from Polygonatum kingianum
Output tracking control for TRMS based on time receding optimal observation of disturbances
No full textThe paper presents an approach to design the adaptive output tracking controller for disturbed Twin Rotor Multi-Input Multi-Output System (TRMS) by using a time receding observer of functional disturbances for compensative control purpose, without using conventional methods as a neural network. To do this, first the disturbed Euler-Lagrange model of TRMS is converted to an equivalent bilinear form. And then, secondly an optimal disturbances estimator for this disturbed bilinear system is constructed based on time receding minimizing their effect. The complete output tracking controller for TRMS is created then by combining an exact linearization controller with the proposed disturbances estimation mechanism. Simulation results show that the here suggested controller meet completely the expected output tracking performances
Improvement of a recombinant β-glucosidase activity of a sequence derived from metagenome database of Binh Chau hotspring
No full textMetabolic products obtaining from microorganisms of geothermal ecologies often show special characteristics which help their cells to survive, grow and develop under extreme conditions. Exploiting the microbial gene resource of those environments demands a new approach via uncultured methods. Thanks to the development of metagenomics and bioinformatic softwares, we can exploit novel genes from environment directly. Based on Binh Chau hotspring’s DNA metagenome sequencing, ORF [denovogenes]_32768 encoding for β-glucosidase is selected for expression into pET17b vector because it shown a low similartity of amino acid sequence as compared to others in Genbank, a high alkali and Tm predicted values. To improve the expression efficiency of β-glucosidase, some factors (host strains, medium culture, IPTG concentration, aeration…) are investigated. The results showed that the recombinant E. coli C43(DE3) reached the highest dried biomass at 8.26 g/L and the maximum enzymatic activity at 0.34 U/mL in shaking condition (TB medium plus 0.25 mM IPTG with the ratio of cultured /flask volume is 20%, 42-48 hours, 30°C). This study demonstrates the capacity of mining a novel gene encoded for enzyme from DNA metagenome of Vietnam hot spring as well as produces recombinant enzyme for biomass conversion
Evaluation of some biophysical characteristics of five silicate solubilizing bacteria isolated from different ecosystems
No full textSilicate solubilizing bacteria (SSB) are key microorganisms to solubilize silicate minerals in the soil. Silicon helps to increase the growth and yield of plants and to enhance the environmental stress tolerance capability of plants. The aim of this study was to evaluate the effect of several factors like pH, salinity, and temperature on silicate solubilizing capacity of five selected SSB. Moreover, phosphorus solubilizing, nitrogen-fixing and indole-3-acetic acid (IAA) synthesizing capacity of these five bacteria were also tested. Liquid soil extract medium containing 0.25% Mg2O8Si3 was used in this study. Abilities of bacteria in phosphorous solubility, nitrogen fixation, and IAA synthesis were tested in NBRIP, Burk’s and NBRIP containing 100 mg L-1 tryptophan media, respectively. The results of the study indicated that five SSB showed their high capacity in silicate solubilization at pH 7.0, NaCl 0.0% and 35oC. However, at a concentration of NaCl 0.5%, these five SSB still solubilized well silicate mineral. Moreover, they also solubilized effectively three different insoluble phosphate sources of Ca3(PO4)2, AlPO4 and FePO4 with a range varied between 105.8 and 928.7 mg P2O5 L-1, 33.9 and 49.6 mg P2O5 L-1, and 1.94 and 34.1 mg P2O5 L-1, respectively. They also fixed biologically nitrogen with a range from 1.37 to 5.09 mg NH4+ L-1 after 2 incubation days. Finally, they also showed their ability in IAA synthesis with an amount between 4.85 and 51.5 mg IAA L-1. In short, these five SSB in this study not only had the ability in silicate solubilization but also had other functions in plant growth promotion
PHENOLIC CONSTITUENTS FROM THE STEM BARKS OF RHIZOPHORA APICULATA BLUME
No full textUsing various chromatographic separations, seven phenolic derivatives (1‒7) were isolated from a methanolic extract of R. apiculata stem barks. Their structures were elucidated to be dunnianoside E (1), (+)-dihydroquercetin (2), 2,6-dimethoxy-[1,4]benzoquinone (3), 2,4,6-trimethoxyphenol (4), 3,4,5-trimethoxybenzyl alcohol (5), hydroxytyrosol (6), and methyl 3,4-dihydroxycinnamate (7) by detailed analysis via spectroscopic techniques (1D, 2D NMR and ESI-MS data) as well as comparison with those reported. This is the first report of compounds 1 and 4‒7 from Rhizophora genus
Growth and metal removal efficiency of the green algae Schroederia setigera and Selenastrum bibraianum exposed to nickel, zinc and cadmium
No full textHeavy metal contamination is among the globally environmental and ecological concerns. In this study we assessed the development of the two green algae Schroederia setigera and Selenastrum bibraianum under exposures to 5 – 200 µg/L of Ni, Zn, and Cd in the laboratory conditions. Heavy metal removal efficiency of S. setigera was also tested in 537 µg Ni/L, 734 µg Zn/L, and 858 µg Cd/L. We found that the exposures with these heavy metals caused inhibitory on the growth of S. bibraianum. The S. bibraianum cell size in the 200 µg Zn/L treatment was around two times smaller than the control. However, Zn and Cd at the concentration of 200 µg/L did not inhibit the growth of S. setigera over 18 days of exposure. The S. setigera also grew well during 8 days exposed to Ni at the same concentration. Besides, the alga S. setigera could remove 66% of Zn, 18% of Cd and 12% of Ni out of the test medium after 16 days of incubation. The Vietnam Technical Regulation related to metals should be considered for ecological protection. We recommend to test the metal removal by the alga S. setigera at pilot scale prior to apply it in sit
TÍNH PHÂN BẬC CỦA ĐỊA HÌNH ĐÁY BIỂN QUANH MỘT SỐ ĐẢO VEN BỜ VIỆT NAM
No full textFlattened seabed characters at the nearshore islands, namely Bach Long Vi, Con Co, Ly Son, Phu Quy, Hon Khoai and Tho Chu, were analysed based on depth contour map with 1 m vertical resolution and the application of ArcMap 10.4 software. Consequently, a series of seabed cross sections was automatically created by using the software, which provides the time-saving benefit and improves the scientific relevance. The result shows that flattened seabed characters of those islands were comparable in terms of general pattern, but still remained some distinctions depending on particular location. The depth of flattened seabed levels does not reach 30–50 m depth at northern and southern Vietnam’s sea (seabed surrounding Bach Long Vi, Hon Khoai, Tho Chu islands), while the value reaches over 100 m depth at southern central Vietnam’s sea (seabed surrounding Ly Son, Phu Quy islands). The classification of flattened seabed reveals the following depth levels: 0–2 m, 5–8 m, 12–14 m, 20–25 m, 25–27 m, 27–30 m, 32–35 m, 40–45 m, 45–50 m, 53–55 m, 60–65 m, 65–70 m, 75–85 m and 90–115 m.Tính phân bậc của địa hình đáy biển quanh các đảo Bạch Long Vĩ, Cồn Cỏ, Lý Sơn, Phú Quý, Hòn Khoai và Thổ Chu đã được phân tích trên cơ sở dữ liệu đo sâu chi tiết với khoảng sâu đều 1m và sử dụng phần mềm Arcgis 10.4. Kết quả phân tích hình thái các mặt cắt địa hình đáy biển, được xây dựng tự động bởi phần mềm máy tính, thể hiện khá chi tiết và đáng tin cậy. Các kết quả cho thấy đặc điểm phân bậc địa hình đáy biển các đảo ven bờ có những nét chung và riêng tùy thuộc vào các khu vực đáy biển khác nhau. Các đảo ven biển Bắc bộ và Nam bộ (Bạch long Vĩ, Hòn Khoai, Thổ Chu) các bậc chỉ thể hiện đến độ sâu dưới 50m, Hòn Khoai chỉ đến 30m, trong khi đó ở các đảo Nam Trung bộ (Lý Sơn, Phú Quí) thể hiện đến độ sâu trên dưới 100m. Tổng hợp chung các bậc địa hình đáy biển của các đảo ven bờ Việt Nam gồm 0-2m, 5-8m, 12-14m, 20-25m, 25-27m, 27-30m, 32-35m, 40-45m, 45-50m, 53-55m, 60-65m, 65-70m, 75-85m và 90-115m
Establishment of a procedure to determine the content of 17 amino acids in soft-shell crab (Scylla sp.)
No full textMud crab Scylla sp. is a common sea crab species in Vietnam as well as in Asia Pacific. Today, mud crabs are raised on a large scale to be harvested at the soft molting stage because of the high economic value of the finished shell crabs. At present, the processing of soft shell crabs is limited to whole packaging and exporting. However, 30% of soft-shelled crabs in processing often lose their feet and claws, which reduce production costs. Therefore, it is necessary to study the technology of processing soft-shell crabs to improve the value of soft-shelled crab products. Recently, the application of enzymes in processing has brought many benefits such as being environmentally friendly and creating many bioactive substances. In this journal, we built the procedure to determine amino acid content in the processing of Scylla sp. to ensure the quality of products obtained after processing. This procedure based on HPLC using a fluorescence reader. The results showed that the amino acid content after hydrolysis process by enzyme technology reached 65.58% dry weight and contains many valuable amino acids such as lysine, leucine, valine, methionine, histidine
A METHOD FOR QUALITATIVELY MAPPING THE FLOOD PHYSICAL VULNERABILITY OF RESIDENTIAL AREAS
No full textMapping flood physical vulnerability is spatially limited because it requires input data such as building structures and materials, which are unavailable on large spatial scales. In this study, we propose a new method for qualitatively evaluating the flood vulnerability of residential areas in the context of the exposure and resilience to flood hazard on large spatial scales. This method utilizes the possible correlations between the structural physical vulnerability and residential types obtained from the statistical classifications of multispectral satellite images. Because multispectral classification is well-established as an inexpensive technique for automatically classifying land cover types over wide areas, our method is feasible and efficient for mapping the physical vulnerability of residential areas. As a case study, we present an application of the proposed approach to the Thach Ha district, Ha Tinh province, Vietnam, using the Japanese type 2 Advanced Visible and Near Infrared Radiometer (AVNIR-2) images and Phased Array type L-band Synthetic Aperture Radar (PALSAR) images captured by the Advanced Earth Observing Satellite (ADEOS)
COMBINATION IMPACT OF pH AND TEMPERATURE ON THE TOXICITY OF LEAD ON ZOOPLANKTON IN THE CONTEXT OF GLOBAL WARMING
No full textHeavy metal pollution in urban lakes of Hanoi has become one of the major environmental issues in the last decades. Research on the toxicity of Pb is necessary due to the extent of its harm to aquatic ecosystems. The toxicity of Pb to aquatic organisms (EC50 values) depends on different environmental conditions. The study was conducted to evaluate the effect of temperature on the toxicity of Pb on the test organism Moina Dubia. Moina Dubia belongs to the Cladocera group (Cladocera) which is an indigenous creature collected at Lake Hanoi. Moina Dubia was cultured under laboratory conditions and has been used to conduct EC50 determination for Pb. Moina Dubia grew and developed well in the laboratory and was suitable as a test organism in toxicological studies. A survey from 24oC to 28oC water temperature conditions showed that the EC50 value decreases from 1402 ug/l to 775 ug/l. The higher water temperature, the higher toxicity level of Pb on Moina Dubia. Clear impact of water temperature on toxicity of heavy metal as Pb showed that global warming may gradually lead to potential biodegradation in freshwater ecology